This is most likely caused by X11 forwarding. Can you try it locally without any forwarding? OpenGL does not always play well with remote desktops, and in those cases there is nothing to do other than avoid remote desktops altogether. There are differences between MuJoCo 1.50 and 1.31 in terms of OpenGL context management, so it is possible that one of them triggers some driver issues while the other one does not.